High Pressure to Maintain the Heat Through Saturday

A high-pressure dome that normally sits over Arizona is parked over San Diego creating a lot of heat that will not let up until Sunday, according to the National Weather Service in San Diego. Though not related, extreme high tides are expected to peak tonight and on the weekend, while El Nino, a warm-water current, is stirring in the Pacific Ocean.

Thunderstorms hovering over the mountains have evaporated, and even the low clouds over the coastal areas have melted away because of the high pressure dome, said forecaster Wilbur Shigehara.

Usually the dome is concentrated in an area of Arizona known as the four corners because the corners of Arizona, Colorado, Utah and New Mexico all meet, said Shigehara. But, because of high-level wind patterns and low pressures in the Northeastern United States and north of Hawaii, the high pressure has shifted to San Diego.

This summer, which has been hot and humid, is very different from last summer when low pressures were concentrated in San Diego and it was very cool, he said.

Last summer, people were complaining it was so cool that they couldn’t go swimming. The temperature Thursday a year ago was 76, compared to a high of 80 for the same date this year. “Since the beginning of the month, we’ve cooked about 5 degrees above the normal.” Even people in La Jolla, where it is usually cool, are complaining it is too muggy, Shigehara said. The humidity is not higher; it’s the normal 60%. But the combination of higher temperatures and humidity makes the weather seem all the hotter.

“It’s the first year since 1985 I’ve seen a high pressure over San Diego as a dominant feature. That’s very unusual. So I’m not surprised to hear people complain the weather is changing.”

The water temperature is several degrees higher than normal too. “Our water temperature is 71; we normally don’t get that high until Labor Day.”

An El Nino or warm water current from the Western Pacific is beginning, Shigehara said. Water temperatures in the mid-Pacific have risen about 2 degrees above normal, but the warm current is weaker than the El Nino in 1982-83 when the water temperature near Christmas Island hit 100 degrees.

Thought not related, the tides driven by the moon and sun, will peak at more than 7 feet today and over the weekend. Today, the high tide will rise to 7.6 feet at 8:43 p.m.; 7.6 feet at 9:29 p.m. on Saturday and 7.3 feet at 10:14 p.m. on Sunday “Fortunately, the waves are only 2 to 4 feet, so the higher-than-normal tides shouldn’t cause any damage,” he said. Just don’t get too near the rocks,” Shigehara said.

The 30-day weather forecast calls for a hot summer right into Labor Day, but a slight cooling trend is expected beginning Sunday, he said. By Tuesday, temperatures will have dropped by about 5 degrees, closer to normal, as the high pressure dome moves closer to Arizona. Mountain areas may see an increase in thunderstorms next week as the high pressure leaves and moisture comes in from Mexico.

At the beaches today and Saturday, temperatures will range from 70 to 78, dropping a couple of degrees on Sunday. The water temperature will rise to 72 with sea breezes at 8 to 15 m.p.h. The coastal strip can expect warm, sunny days with the mercury rising to 79 to 87, notching down a few degrees on Sunday. Nighttime temperatures will drop down between 67 and 73.

Inland areas will see highs of 88 to 98 and nighttime lows of 63 to 70 through Sunday, Shigehara said. The mountain areas will experience partly cloudy afternoons with a slight chance of thunderstorms, he said. Temperatures will range from 81 to 89, dipping down a few degrees Sunday, with nighttime lows of 56 to 66.

Temperatures in the deserts will soar to 108 to 116, nudging down to 114 by Sunday. Nighttime lows will range from 78 to 86 degrees.